And howell c



1. B. GARNER AND H. c. COOPER. RECOVERY OF BUTPLNE AND PROPANE.

APPLICATION FILED AUG.5. 1916.

1,307,353. Y PatentedJune24, 1919.

3 SHEETS-SHEET l.

Q. :5 S m Q- F I E] E a k l E s 1 k\ WITNESSES INVEYNTORS APPLICATIONFILED AUGHI I9I6v J. B. GARNER AND H. C. COOPER.

RECOVERY OF BUTANE' AND PROPANE.

m KEANE Po Au Q.

WITNESSES I. B. GARNER AND H. C. COOPER.

RECOVERY OF BL'TANE AND PROPANE.

; APPLICATION FILED AUG.5. 1916 1,307,353.

m mm QM 1T 11E 2 M s m; 6 hm 7 d H m p w t a P JAMES B. GEEK, '01PITTSBURGH, PENNSYLVANIA, HOWELL C. COOPER, 0F =URG, WEST VIRGINIA,ASSIGNOBS TO HOPE NATURAL GAS COMPANY, OF

PITTSBURGH, IENNSYLVANIA, A GORPOEATION OF WEST VIRGINIA.

RECOVERY OF BUTAI'I' E AND PROPANE.

Specification of Letters ream. Patented June 24, 1919.

Application filed August 8', 1916. Serial No. 113,800.

To all whom it may concern: I

Be it known that we, JAMES B. GARNER,

residing at Pittsburgh, county of Allegheny,-

and State of Pennsylvania, and Hownnr. C. COOPER, residing atOlarksburg, in the county of Harrison and State of West Virginia, bothcitizens of the United States, have invented or discovered certain newand useful Improvements in the Recovery of Butane and Propane, of whichimproveto be constituents, in varying proportions,

of natural gas and of oil also. They are gases under normal atmosphericconditions of. pressure and temperature. Aside from their existence insuch hydrocarbon mixtures of natural origin, there is, to the best ofour knowledge, no other known-source of butane and propane, and such ashave been commercially produced have been prepared synthetically. Butalthough known to be constituents of hydrocarbon mixtures of naturalorigin, their. separation from such mixtures has not heretofore beenaccomplished commercially. However, if obtained economically on acommercial scale, each substance has great commercial value as aliquefied homogeneous combustible gas suitable, for example, forheating, for cutting and welding metals, and for internal combustionengines.

For various reasons it is essential that a liquefied hydrocarbon gas forsuch purposes be homogeneous. In the first place, for

shipment it must, of course, be placed in pressure fl asks, and it isnecessary, in fact it is a requisite for interstate shipment, to

know the pressure to which such filled flasks may, under differenttemperatures, be sub jected. If the liquid be not a homogeneoussubstance, the pressure which it Wlll exert on its flask or containercannot, because of varying partial pressures, be predicted. In-

the second place, if the liquid gas be not'jai-i. homogeneous substance,that 18 to say, 1f--1t' be a mixture of various hydrocarbons, the

first gas used from a filled flask will include in its mixture a largerpercentage of the lighter and more volatile h drocarbons than will thegas last used. onsequently, the heating value or B. T. U. of the gasfrom a single flask will vary as the flask'is emptied,

the gas first used having a lower B. T. U. than that last used; theamount of oxygen required to be mixed with the'gas will vary; and aburner, jet or carburetor suitable for the first portion of the gasdelivered from the container will be unsuitable for the last portiondelivered therefrom.

In the course of our experimentation we have endeavored in Vain toseparate these components from natural gas containing them, bysubjecting the gas directly to the normal operation of fractionalcondensation: that is to say, by gradually increasing pressure, tocondense one component after another, as the point of liquefaction ofthe several components is successively attained. For reasons notcertainly known butane and propane cannot be thus separately recovered.

In an application for United States Letters Patent filed by us on June8th, 1916. Serial No. 102,489, we have described a pro cess of obtaininggasolene from natural gas consisting in certain improvements upon theprocess for that purpose described and claimed in United States LettersPatent No. 989,927 to George M. Saybolt, one of the purposes of the saidimprovements being the more efl'ectiv-e separation from the normalliquid product of the said. Saybolt process, of the so-called lightercombustible constituents of the gas. In the practice of the presentinvention we prefer to employ the appa ratus shown in the drawings ofour sald pending application, and it is therefore illustrated in Figures1 and 2 of the accom-- panying drawings. Fig. 3 shows a form ofapparatus which we prefer to employ for the performance of the laststeps of our present invention. It will be understood however that otherforms ofapparatus may I tensed/it desired, and that shown may alsocooler 3, and. by pipe 6 into the lower ab sorber 4 of a pair ofobsorbers 4 and 5. The

portion of pipe 6 'within the absorber fl is perforated, as indicated,so that the compressed gas is made to bubble up through a body Ofabsorbent menstruumas will presently be described. The gas which isunabsorbed by the menstruum in the absorber 4 is caught in a perforatepipe or header 7, and thence passes through a pipe 8 to a perforate pipe9* near the bottom of the absorber 5, and thence'flows through absorbentmenstru-um contained in this absorber. The remaining unabsorbed gas iscaught in a perforate, pipe or header 10 and flows out through the pipe11 to the gas line.

The absorbent menstruum is made to flow through the absorbers in adirection opposite to that of the flow. of the gas. The menstruum entersthe absorber 5 through the pipe 12, andfas viewed in Fig. l, flows fromright to left to a pipe 13 leading downwardly into the left end of theabsorber 4,

through which it flows from left to right to a pipe 14. Suitablepartitions or dams l5,

' 16 are provided in the absorbers in order to suflicient weight toovercome all permissible.

maintain therein a body of menstruum of suitable depth:

As is stated in the. S'aybolt patent above referred to various l-iquidsmay be used as an absorbent menstruui'n; We prefer to usehowever apetroleum hydrocarbon having an initial Baum gravityof from 28 to 55, at60Fahrenheit. Then the apparatus is operated as thus far explained,under conditions of pressure and temperature Well understood by thoseskilled in the art, the result is the absorption in the menstruum contained in the absorbers 4 and 5 ofpvapors which are contained in thenatural gas and which. when condensed constitute what is commericallyknown as gasolene, together with certain other lighter hydrocarbons, invarying quantities dependent upon conditions of operation, which aregaseous at at mospheric pressure and temperature, and which includebutane and propane.

From rthe absorber-4 the menstruum, now

enriched by the hydrocarbons which it has been caused to absorb from thenatural gas,

' flows through the pipe 14 into the primary still, consisting of theupper retort 17 and the lower retort 18, which maybe heated to thedesired degree in any suitable way, but preferably by means, of thesteam pipes to be presentl described. In the apparatus illustrated,'tepressure of the absorbers is maintained in the still, and in order toprevent gas from flowing from the absorber 4 into the retort 17 or thevapor from the retort 17 flowing into the absorber 4, a trap 19 isformed in the pipe 14, the vertical length of each leg of which is 'suchas to. provide a column of the liquid enriched menstruum of or likelydifference in pressure between the absorber 4 and the retort 17.

In the top of the retort 17 is a perforate pipe or header 20, throughwhich the enriched menstruum is condicted from' the pipe 14 and. fromwhich it flows over the steam pipes within the retort. .From the :bottomof the retort 17 the mefistruum flows through a pipe 21 into the bottomof the retort 18,

through which retort it flows, in a devious,

path determinedbythe bafiie plates 22, to the discharge pipe 23. In theapparatus shown a supply of hot water or'steam is taken from the heater24 (Fig. 2) and flows through a pipe 25 into the retort 18, and fromthence through a pipe 26 into the pipes in retort 17, and thenceoutthrough an escape pipe 27.

The function of the retorts 17 and 18 is to distil off from the enrichedmenstruum preferably only lighter constituents which have been absorbedfrom the gas, and which are gaseous at atmospheric pressure andtemperature. Hence the temperature maintained in these retorts iscomparatively low, say from 95 to 110 F. And the pressure, as alreadystated, approximates the pressure in the absorbers, so that thosehydrocarbons which have been absorbed from the gas,

which are liquid at atmospheric temperature and pressure shall remainfor the most part still contained in the enriched menstruum.

The lighter hydrocarbons which are'distilled out of theenriched'menstruumv in the retorts l7 and 18 pass from the retort 18through the pipe 32 into the retort 17 and thence all of such distilledhydrocarbons ,pass out of the retort 17 through the pipe 30;or in thealternative the hydrocarbonvapors in the retort 18 may l:pass outthrough the pipe 31 into pipe 30. rom the plpe 30 these lighter gaseoushydrocarbons may pass directly through the pipe 58 into the line 11; or,as described in our application referred to; they "may be pumped by thepump 34 in the pipe 33 through a cooler 35 and liquefied products bedeposited in receptacle 36, while still uncondensed vapors may passthrough the pipe 37 to the line 11. Or the apparatus may be operatedunder such conditions bf pressure and temperature, as is well understoodin the art, that the vapors in the pipe 11E recovery of propane and theprimary distillation. Referring now to Fig. 2, the menstruum (stillcontaining the e hydrocarbons and usually still some of the lighterhydrocarbons) passes from the bottom of the retort 18 through the pipe23, which is provided with a pressure reducing valve 45, into the heatexchanger 43, whence it passes through the pipe 46 into the still 38.Within the heat exchanger 43 there is arranged a pipe system into whichflows from the still 38 through the pipe 44 the hot denuded menstruum,which serves to heat the enriched menstruum flowing through theexchanger 43 on its way to the still 38. The lower part of the still 38is provided with suitable pipes adapted to be heated by steam flowingfrom the header 39 at one end of the still to a similar header 40 at theother end thereof, these headers being provided with suitable steamconnections. However steam may be admitted'directIyto the still 38through the jets 41 connected to a steam supply pipe 42..

llithin the still.38 there are arranged suitable baffles 54 to cause themenstruum to flow in a devious path from one end to the other.

Because of the reduced pressure and the increase of temperature of theenriched menstruum in the heat exchanger 43, some ofthe containedhydrocarbons may be volatilized, and in order not to interfere with thedistillation in the still 38 it is desirable that these vapors be drawnoff through a trap I The conditions of temperature and pressure withinthe still 38 are such as to effect the distillation from the enrichedmenstruum of its absorbed gasolene content, usually however togetherwith certain quantities of gaseous propane and butane. The distilledvapors pass out from the still 38 through thepipe 49 (which may beprovided I with a suitable steam ejector 51) into the condensing coils50, from which "the liquid product flows through'the pipe 53 into theclosedstorage tanks 52, 52. The water, if any, and the 'gasolene, willbe separated in'the storage tanks, and each may be drawn off separatelyas desired or found necessary. The pressure in the still 38, condensercoils 50, and tanks 52 and 52 may be maintained below a desired maximumby the use of a suitable relief valve placed in a tap 79 con.- nected tothe pipe 59 leading from the tops of the storage tanks.

The still uncondensed vapors (namely butane and propane) in the storagetanks 52, 52, pass out through the pipe 59. In order to insure theattaining of a substantially pure mixture of gaseous butane and propaneuncontaminated by any heavier hydrocarbon vapors, we preferably pass theuncondensed gases in the pipe 59 through a supplemental absorber orabsorbers, wherein any pentane or other heavier hydrocarbon remaining invapor formin the uncondensed gas will be absorbed, and a substantiallypure mixture of butane and propane will be obtained for furthertreatment. To this end we have shown the pipe 59 connected by pipes 60and 61 with the bottoms of a pair of absorbers and'56, which are adaptedto contain amenstruum capable of absorbing .any of these heavierhydrocarbons. This menstruum will preferably be what is commerciallyknown as sun spirits, a liquid hydrocarbon of the paraffin series havingat F. a Baum gravity of about 337. The

filtration "will conveniently be carried on under normal atmosphericconditions of pressure and temperature. It may if preferred be carriedon at a pressure greater than atmospheric, but less of course than theliquefaction pressure of butane. The sub division of the gas undertreatment such as to cause it to bubble up through the menstruum in afinely divided state, and so to come into more intimate contact with themenstruum and to be more thoroughly cleansed and purified, will beaccomplished according tothe well recognized principles of thatoperation. Connections are shown in the drawings whereby the gaseoussubstances in the pipe 59 may be caused to flow through the absorbers 55and 56, either in series or in parallel, but such connections and theappliances connected therewith are well understood and need not beherein describedin detail.

From the tops of the absorbers 55 and 56 i the unabsorbed gases, now.substantially a treated is introduced in increasing quantities'and withincreasing pressure.

We continue to pump into this compression-chamber quantities of the gasto be reduced until, in consequence of increasing pressure, aliquefaction has taken place. The occurrence of such liquefaction may bedetected by opening from time to time one and another of the pet cocks70 with which and through this inlet the mixture to be the compressionchamber 69 is equipped at collects at the lower end of compressionchamber 69, whence it is drawn off by gravity, through avalve-controlled duct 71, to a suitable storage tank 72. The inlet pipe68 will meanwhile preferably have been closed. Thus a fractionalcondensation is achieved upon a natural-gas derivative which has beenessayed in vain upon the gas itself.

WVhen the butane in liquid condition has been so drawn off there remainsin compression-chamber 69 a body of substantially pure propane ingaseous form. The further operation involves compression of the propaneto the point of liquefaction; this may e accomplished in any desiredmanner, and we shall here describe the means We have actually used,though other means manifestly may be employed. WVater impelled bypressure is introduced at the lower end of compression-chamber 69through a suitable connecting pipe 73, and this entering column of wateris forced in, mounting up in chamber 69 and compressing the propane atthe upper end of the chamber, until (under unmodified temperatureconditions) a pressure upon the gas of about 650 pounds to the squareinch is attained. At this point the propane liquefies (a change which,again,

v, Pressure wise). lVhen the propane has been so liquefied a duct 74 isopened, and through-it the liquid propane is driven by the mountingcolumn; of water, through a cooler 75, if need be, to a storage tank 76.As the column of water mounts in the chamber 69, driving liquid propanebefore it, the height of its rise may be detected at the pet-cocks,andwhen it is detected at pet-cock 7O at the upper end of thepressure-chamber, the impelling pressure is cutoff and duct 74 isclosed. The storage tanks 72 and 76 may then be detached; valves maythen be opened, the pressure-chamber drained, fresh storage tankssupplied, and the apparatus will thus be made ready for repetition ofthe operation now described. 77 is apressure-gage which we have foundconvenient to employ to assist and facilitate our work. gages maybe usedelsewhere, if desired.

Our work in the premises (as has been intimated above) has had to dowith a natural-gas derivative in which the butane. and propanecomponents are, in terms'of weight, present in substantially equalquantities. It is conceivable (though the fact lies beyond'the range ofour experimenta tion) that, given a gas in which these components arepresent in distinctly unequal proportions, some variation may be foundin pursuing our method in the critical pressure required to condense andseparate the butane component from the propane. While we have in theensuing claims defined our invention according to the specific pressureswhich, under existing conditions, we have found correct, we recognize aswithin the scope of our invention and mean to include within the meaningof our claims such departures from the figures given, in this matter ofcritical pressure, as, in the case of compounds of other proportions,experience may find requisite. Of course, if for any reason it is founddesirable to operate at temperatures other than substantially normalatmospheric, the critical pressures will vary accordingly, and We meanto include in the scope of our Letters Patent pressures equivalent tothe pressures given proper allowance being made for substantialdepartures from normal atmospheric tem- 95 perature. I

We have described our invention as having to do with natural gas, and,more specifically, with certain refined derivatives of natural gas. Itwill be understood that mixtures of butane and propane may be detunes,from whatever particular source derived.

We claim as our-invention:

1. The method hereirLdescri'bed of recovering butane from petroleum and'natural gas and derivatives thereof which consists in isolating asubstantially pure mixture of butane and propane alone and thensubjecting such mixture to fractional condensation.

2. The method herein described of recovering butane and propaneseparately and each in liquid form which consists in isolating asubstantially pure mixture of butane,

and propane alone, forcing the mixture into a suitable chamber until thecondensation ing a substantially pure mixture of the butane and propanealone, and then separating said mixture of butane and propane into itsconstituent elements. i

- 4. The process of recovering butane from a gaseous mixture of butane,propane and other hydrocarbons, Which consists of subjecting suchmixture to an absorbing menstruum and by the aid thereof absorblng thebutane and propane, distilling said menstruum for the removal therefromof butane andpropa'ne, subjecting the distillate to a substance capableof absorbing from the distillate the hydrocarbons heavier than butane,and separating therem'aining substantially pure mixture of butaneandpropane into its constituent elements.

5.. The process of treating a gaseous mixture of butane, propane andhydrocarbons heavier than butane, which consists of subjecting suchmixture to a liquid hydrocarbon of about 33.7 B-aum gravity and bytheaid of said liquid absorbing said heavier hydrocarbons, and thenseparating the remaining gaseous mixture of propane and butane into.

distillation the butane and propane com ponents; third, in filtering thedistillate through a naphtha-absorbing substance;

and, finally, separating the butane from the propane by fractionalcondensation.

In testimony whereof we have hereunto set our hands.

JAMES B. GARNER. HOWELL o. oooPER.

Witnesses:

BAYARD H. CHRIsTY, V FRANCIS J. ToMAssoN.

